The invention relates generally to power-driven conveyors and, more particularly, to modular plastic conveyor belts suitable for following curved paths.
Conveyor belts are typically used for conveying bulk material, such as foodstuffs or other materials, that must be transported through a cooled or refrigerated environment. Typical conveyor belts have the advantage that relatively little energy is required for transporting the bulk material across horizontal surfaces. The conveyance of bulk material, however, is limited by such systems to horizontal routes or to routes with only relatively small inclines. To overcome greater heights or inclines, it is necessary to transfer the bulk material to another conveyor system, for example, a bucket chain conveyor. In the transport of material to be refrigerated, it is often desirable to maximize the time of transport within the cooled environment. It is desirable to provide a conveyor belt system that transports goods along an extended path.
Spiral conveyor belts, in which a conveyor belt follows a helical path, are used in certain applications because they allow for an extended path with minimal floor space. For example, spiral conveyor belts are often used in freezers and ovens to provide a long conveying path with a small footprint.
Self-stacking spiral belts are used to form a helical path with minimal framing. A self-stacking conveyor belt uses side plates or side guards coupled to the side edges of the conveyor belt to form a self-supporting stack. The belt travels in a straight path until it enters a spiral or helical configuration. When aligned in the helical configuration, the lower tier of the belt is supported by a frame or drive system, while the upper tiers are supported by the lower tiers. The interface between adjacent tiers is designed to keep the belt supported and laterally aligned. The tiers are laterally aligned by resting the upper edge of a lower side guard against the bottom side edge of the belt in a tier above.
In large spiral freezers, there are generally two different types of airflow used to cool product. The first is vertical airflow. In vertical airflow, air is forced from either the ceiling or the floor through the belting and out the opposite end (floor or ceiling). The air is forced through all the tiers of belting and product to produce convective airflow over the product. Another type of airflow used to cool product is horizontal airflow. In horizontal airflow, air enters from one side of the spiral and exits out of the other side so that the air flows horizontally across the belt.
Many self-stacking spiral belts on the market today prevent adequate horizontal airflow.
In freezer applications, or other applications in which the temperature varies widely or quickly, the tiers tend to push out of alignment, causing the belt to destack.